Foraminous structures

ABSTRACT

A foraminous structure having a plurality of walls, each extending between pairs of spaced surfaces which are disposed in staggered relationship along a common plane. The walls are pivotally connected to edges of the spaced surfaces between which they extend and may be disposed, relative thereto, at an angle approaching 180 degrees.

Sept. 11, 1973 T. FAIRBANKS FORAMINOUS STRUCTURES 2 Sheets-Sheet 1Original Filed Feb. 16, 1970 Seiai. 11, 1973 T. H. FAIRBANKS 3,758;372

- FORAMINOUS STRUCTURES I Original Filed Feb. 16, 1970 2 Sheets-Sheet 2United States Patent 3,758,372 FORAMINOUS STRUCTURES Theodore H.Fairbanks, Liverpool, Pa., assignor to FMC Corporation, Philadelphia,Pa.

Original application Feb. 16, 1970, Ser. No. 11,510.

Divided and this application July 22, 1971, Ser. No. 165,285

Int. Cl. B32b 3/10 US. Cl. 161-109 6 Claims ABSTRACT OF THE DISCLOSURE Aforaminou s structure having a plurality of walls, each extendingbetween pairs of spaced surfaces which are disposed in staggeredrelationship along a common plane. The walls are pivotally connected toedges of the spaced surfaces between which they extend and may bedisposed, relative thereto, at an angle approaching 180.

This application is a division of my application Ser. No. 11,510, filedFeb. 16, 1970.

The invention relates to foraminous structures.

In my US. patent application Ser. No. 714,231, now US. Pat. 3,616,025,there is disclosed a method for making foraminous or cellular structuresin which a pliable web material is slit along only a portion of thelength of each of a series of lines defining a plurality of abuttingparallelograms, with the slits of the individual parallelograms meetingor intersecting at only one pair of diagonally opposed corners thereof.The slits of such individual parallelograms terminate short of theirother pair of diagonally opposed corners and thus the ends of such slitsare separated by narrow neck sections of web mate rial. Each of theportions of the web material extending between these neck sections isthen pivoted as a planar unit by twisting the Web material in the areaof the neck sections into a helical configuration. The free corners ofthe individual parallelograms; that is, the diagonally opposed cornersthereof at which the slits meet, are thus moved in opposite directionsaway from the plane of the original web material.

In view of the twisting of the web material in the areas of the necksections, the above-described method is not particularly suited for usewith non-ductile, rigid or easily torn web materials, as for example,cellulosic films or paper. Accordingly, a primary object of thisinvention is to provide a generally new or improved and moresatisfactory foraminous structure.

Another object is the provision of an improved foraminous structurewhich is light in weight, possesses good structural volume, rigidity andstrength and can be made with low manufacturing costs and frominexpensive materials, including web materials which are non-ductile,rigid, or easily torn.

Still another object is the provision of an improved integral foraminousstructure formed of a single web material in which stress concentrationsare at least minimized to avoid tearing areas thereof.

A still further object is the provision of a foraminous structure havinggenerally rectangular openings which are reinforced along portionsthereof.

A still further object is the provision of an improved composite producthaving a honeycomb structure as a core.

These and other objects are accomplished in accordance with the presentinvention by foraminous structure which are formed by a method in whicha Web material is provided with rows of like, equally spaced cross-cuts,each of which is comprised of a pair of slits of equal length crossingsubstantially centrally of and at right angles to each other. Eachcross-cut is arranged with ends thereof located along a common linepassing through the ends of slits of ice an adjacent cross-cut. Moreparticularly, cross-cuts, as defined above, are located at the cornersof an array of abutting squares. One slit of each such cross-cut extendsat an angle of 45 +9 to a line joining its center with the center of anadjacent cross, with 0 being an angle which is greater than zero butless than 45. Portions of the web material which extend between adjacentcross-cuts are then pivoted as integral units by urging the same aboutaxes which are generally coincident with the common lines passingthrough the ends of slits of the adjacent cross-cuts between which therespective web portions extend.

Each of the portions or units of the web material which extend betweensuch adjacent cross-cuts can perhaps be best described as consisting ofa pair of like surfaces, each having the configuration of an isoscelestriangle. Slits of the adjacent cross-cuts extend only along the sidesof the respective triangular surfaces which are of equal length, whilethe remaining sides of these triangular surfaces are disposed inabutting relationship along the common line passing through ends ofslits of such adjacent cross-cuts. These remaining or unslit sides ofthe triangular surfaces are not in abutting relationship along theirentire lengths, however, and thus the triangular surfaces are offsetfrom each other along the common line passing through the ends of slitsof the adjacent cross-cuts. In view of the offset relationship of thetriangular surfaces, the diagonally opposed free corners of such pair oftriangular surfaces are also offset from each other; that is, locatedequal distances from opposite sides of a plane bisecting, at rightangles, the common line which passes through the ends of slits ofadjacent cross-cuts.

Ideally, portions of the web material which are to be pivoted are turnedabout individual axes which are coincident with the common lines passingthrough the ends of slits of adjacent cross-cuts. In this manner theportions are pivoted as planar members; that is, without flexing andwithout creating stress concentrations, at which tearing may initiate,in the areas at which such portions remain attached to the original webmaterial.

Included within the scope of the present invention are foraminousstructures in which portions of the web material are pivoted as integralunits but with sections thereof turning about lines which are slightlyaskew to the ideal pivot axes described above. This effect isexperienced particularly when the turning forces are concentrated at oneor both of the diagonally opposed free corners of the pair of triangularsurfaces comprising such portion.

With a stiff or rigid web material, the pair of triangular surfacescomprising each such portion generally act together as a rigid body sothat it is immaterail whether a turning force is applied to either orboth of the free corners thereof. Thus, a turning force applied to oneof these free corners tends to cause both of the triangular surfaces topivot as a unit about the ideal pivot axis, along which are located theabutting sides of such triangular surfaces. Under such turning forces,it appears that there is also a tendency for each of these triangularsurfaces to pivot, respectively, along an axis which is in line with aslit extending along one side of the opposing triangular surface. As aresult, pivoting does occur about the ideal pivot axis along that areain which unslit sides of the triangular surface are in abuttingrelationship. However, in each of the areas of the triangular surfaceswhich are adjacent to the remainder of such unslit sides pivoting occursalong axes which are between the ideal pivot axis and an axis in linewith the slit side of an opposing triangular surface.

In one embodiment of the invention the pivoted portions or units of theweb material are disposed in rows which are in generally parallelrelationship with each other. In such structure the units may be pivotedto the same or different angles relative to the plane of the originalweb material, which angles may approach 180 from their originalpositions. If necessary, the units are fixed in their pivoted positionsand,when moved through the maximum degree noted above and fixed inplace, a structure is provided having openings Which are reinforced atleast along sections thereof.

In an alternative and preferred embodiment of the invention, the unitsor portions of the web material which are pivoted are disposed in rowswith each such row of units intersecting at generally right angles withanother row of pivoted units. Such units may also be pivoted to the sameor different angle relative to the original plane of the web material,which angle may approach 180. When such units are pivoted through anangle of substantially 90, a honeycomb structure is provided. Acontinuous sheet may be disposed along one or opposite sides of suchstructure and attached to the outermost ends of the pivoted units toprovide a rigid panel having good strength properties. On the otherhand, pivotting the units through an angle approaching 180 and fixingthe same in place provides a formaminous structure having generallyrectangular openings which are reinforced along sections thereof.

Once portions of the web material have been pivoted as described above,the areas of the original web material which remain are in the form ofspaced surfaces, all of which, of course, are in a common plane. Each ofthe pivoted units is actually a wall which extends between and isattached to a pair of such spaced surfaces and, of course, is disposedat an angle thereto. As heretofore mentioned, the units or walls arearranged in parallel rows. If pivoted to the same degree the units orWalls of one row will all be disposed in generally parallelrelationship. Such walls, however, will be in staggered relationshipwith the units or walls in adjacent parallel rows and will be alignedwith Walls which are remote from such adjacent rows.

In all embodiments of the invention, the portions or units or walls ofthe web material which are pivoted or turned each include a pair ofcorners which are formed by free edges extending along converging planesfrom the areas at which such portions are pivoted or hinged to theremainder of the web material. In the ideal and preferred arrangementheretofore mentioned, the portions of the web material are pivoted asplanar members so that tearing or twisting of the web material at thelocations of hinging is avoided. The spaced surfaces to which suchpivoted planar portions or walls are attached are of generally squareconfiguration, with the planar walls being hinged to such squaresurfaces along the edges thereof. In the other of the embodiments, thesespaced surfaces are of generally zig-zag form, with the pivoted portionsor walls being hinged to straight edges thereof.

As described above, each cross-cut is arranged with the ends of slitsthereof located along a common line which passes through the ends ofslits of an adjacent cross-cut. Thus, the lengths of the slits of thecross-cuts and the spacing of such cross-cuts are interdependent andboth are varied' when it is desired to change the size of the portionsof the web material which are to be pivoted.

The terminalogy cross-cut, as employed throughout the disclosure, isintended to include like slits crossing each other centrally and atright angles to each other, regardless as to the manner by which suchslits are formed. Thus, While such crossing slits are perhaps mosteasily formed by actual cutting of the web material, they may be alsoformed, for example, as by melting, burning or dissolving portions ofthe web material.

The method employed in making the formaminous structures of the presentinvention is particularly useful with materials which have lowductility, or are rigid or are easily torn, as for example, cellulosicfilms and paper. The described method is equally Well suited for usewith pliable or ductile materials such as materials which arethermoplastic, for example polyamides or superpolyamides, polyesters,polyvinyl chlorides, and copolymers thereof, polyolefins, and celluloseacetates; thermosetting materials, sheet metals, such as aluminum,copper, brass, sheet steel; fabrics; impregnated fibrous webs; etc.

With the exception of the web materials formed of ductile materials, itis generally necessary to set the pivoted portions of the web materialto fix the same in position. Thus, with web materials which are ofthermoplastic character, the portions of the Web material which extendbetween adjacent cross-cuts or the areas of such portions which are tobe flexed may, for example, be in a heat softened condition while theyare being pivoted and then cooled to set the same in fixed positions.Thermosetting web material may, of course, be set by heat, whilematerials, such as paper, fabrics, or fibrous webs, may be fixed by theapplication of coatings or activation of coatings or impregnatingmaterials already present to stabilize the same. When pivoted portionsof the web material have been moved through an angle approaching 180from their original planes they may be fixed or sealed in such positionsby adhesive or, in the case of thermoplastic materials, by fusion.

As heretofore mentioned, a continuous sheet, web material or other flatmember may be attached to one and desirably both sides of the preferredformaminous structure of the present invention to provide a panel orcomposite product having great strength and rigidity. Attachment of suchcontinuous sheet may be effected, for example, by adhesives, fusion orperhaps by projecting the free corners of the pivoted walls throughsuitable slots in the sheets themselves, after which such corners may bedistorted as by bending, twisting, or may be fused to the sheets to lockthe same in place.

In the panels or composite products described, it will be apparent thatsheets fixed to the cellular or honeycomb core structure maintain thepivoted walls thereof in fixed positions. Moreover, such attached sheetsserve also to distribute loads over a large area of the composite prodnet and, if desired, may be made fluid tight to impart buoyant andperhaps heat insulation characteristics to such product.

The continuous sheets or flat members may be formed of any desiredmaterials and may be the same or different from that of the honeycombstructure itself. Such sheets may include the various additives, such ascolorants, stabilizers, etc. and, in the case of plastic material may beof transparent or translucent character.

Apparatus for use in making the foraminous structures of the presentinvention includes means for providing a pliable web material withspaced rows of cross-cuts, arranged as described above, and means, suchas suitable projections, for engaging at least one and preferably bothdiagonally opposed free corners of the units or portions of the webmaterial located between adjacent cross-cuts for pivoting the same asintegral units by urging the opposed free corners thereof in oppositedirections relative to the plane of the original web material.Preferably, the apparatus is designed for continuous manufacture of theforaminous structures of the present invention. Thus, the means forcutting the web material as well as the projections may be carried bysuitable pulleys or belt conveyors so as to permit the same to performtheir intended operations on a web material concomitantly with itscontinuous travel.

\As with the apparatus disclosed in my above-noted Patent No. 3,616,025,the apparatus may also include means for providing a continuous sheetwith slits at spaced locations corresponding to the spacing with thepivoted portions of the web material, means for disposing the slit sheetonto the pivoted portions of the web material so that such portionsproject partially through the flat sheet, and means for distorting theprojecting partitions of the pivoted portions of the web material tothus lock the sheet in place.

Under this same moment there is a tendency for pivoting to occur alsoalong the lines FL and J M. It appears, however, that this lattertendency is partially offset by the moments encouraging the triangularsurfaces AF] and DLM to pivot about axes which are in line,respectively, with the sides DL and AJ. The net result of these momentsis that pivoting also occurs along axes as indicated at 45 and 47 inFIG. 2, with axes 45 extending between the ideal pivot axis and an axisin line with the side DL while the axis 47 is disposed between the idealpivot axis and an axis in line wth the line A].

While pivoting of the respective portions 43 as described above willoccur under certain applications of forces, and the foraminousstructures provided by this procedure are considered to be within thescope of the present invention, for simplicity and ease of description,the remainder of the detailed description is primarily confined to amethod in which the portions 43 are pivoted about the ideal axes asindicated by the lines 39 and 41, and the structures formed thereby.

In FIG. 4, the portions of the web material 43, extending betweenadjacent cross-cuts 29 in adjacent rows of cross-cuts are illustrated asbeing pivoted as planar units through an angle of less than 90 relativeto the plane of the original web material 31. The portions of the webmaterial extending between adjacent cross-cuts 29in alternate rows ofcross-cuts are indicated by character 49 in FIG. where they areillustrated as being pivoted similarly to the planar units 43 of FIG. 4.

The respective FIGS. 6 and 7 show the portions of the web material orplanar units 43 and 49 after being pivoted through an angle of 90 out ofthe plane of the original web material 31. Pivoting of the planar units43 and 49 into positions shown in FIGS. 4-7, may be achieved by anysuitable means. For example, as shown in FIG. 8 a pair of triangularprojections 51 and 53 may engage with the free end portions of anindividual planar unit 43 or 49 from opposite sides of the web material31 and thus pivot the same about its respective pivot or hinge axis 39or 41. The projections 51 and 53 are of like cross-section, each havingthe configuration of an isosceles triangle in which like sides 55 and 57are of a length slightly less than one-half of the cross-cut slits 33and 35. As disclosed in my above-noted pending application, projections51 and 53 may be provided along opposing surfaces of a pair of movableendless belts so as to permit such projections to pivot the planar units43 and/or 49 concomitantly with the advancement of the web materialbetween and together with such belts.

FIGS. 9 and 10 illustrate the planar units 43 and 49 of the web material31 pivoted still further from their positions shown in FIGS. 6 and 7,and approaching an angle of 180 from the plane of the original webmaterial. The planar units 43 and 49 may be fixed, as by sealing, intheir positions shown in FIGS. 9 and 10 to i provide a foraminousstructure having openings as indicated at 59 in FIG. 9 and at 61 in FIG.10.

The foraminous structure shown in FIG. 11 incorporates the teachings ofthe structures shown in FIGS. 4 and 5 with both the planar units 43 and49 being pivoted less than 90 from their original positions about therespective lines 39 and 41. Likewise, FIG. 12 illustrates a structure inwhich the planar units 43 and 49 are both pivoted substantially 90 fromthe plane of the original web material 31, while in FIG. 13, the planarunits 43 and 49 are shown in positions assumed after being movedsubstantially 180 from their original positions. In this latterstructure, the planar units 43 and 49 define openings 63, and may besealed in their pivoted positions, as by heat in the case of athermoplastic web material, to reinforce the openings at least at thecorners thereof.

The forarninous structure shown in FIG. 12 is of honeycombconfiguration. A continuous sheet 65 may be attached to one or bothsides of this particular structure to provide a panel 67, as shown inFIG. 14, which exhibits good strength yet is light in Weight and rigid.The sheets 65 may be attached to the foraminous structure, for example,by fusing the same in place, in the case of thermoplastic materials,adhesives, etc. Alternatively, portions of the free ends of the pivotedplanar units 43 and 49 may be extended through suitable slots in thesheets 65 and then twisted to lock such sheets in place.

The various embodiments of the foraminous structures described areadapted for various uses. The structures shown in FIGS. 4-7 and 9-13 areboth decorative and functional and may be employed in such applicationsas packaging materials, article separators, ventilation screens, roomdividers, temporary road and landing mats, fencing, mats for preventingbeach erosion, etc. The panel illustrated in FIG. 14 is useful as astructural member, as for example, flooring, walls, roofs, partitions,article spacers, pallets, etc.

It is to be understood that changes and variations may be made withoutdeparting from the spirit and scope of the invention as defined in theappended claims.

I claim:

1. An integral foraminous structure formed of a unitary web material,said structure having rows of spaced, planar walls, each of said wallsdefined by adjacent of a plurality of like, equally spaced cross-cutsformed in rows in a web material with each of such cross-cuts beingcomprised of a pair of slits of equal length crossing substantiallycentrally and at right angles to each other and also with each cross-cutarranged with the ends thereof located along a common line passingthrough the ends of slits of an adjacent cross-cut, said rows of planarwalls being disposed, by being flexed as integral units, at an angle tothe remainder of the web material with the walls in each row of wallsbeing in staggered relationship with the walls in adjacent rows and inaligned relationship with the walls in rows remote from such adjacentrows, the remainder of the web material being in the form of similarspaced surfaces disposed in a common plane.

2. A structure as defined in claim 1 wherein said walls are flexedsubstantially relative to the plane of said surfaces and project beyondopposite sides of said surfaces.

3. A structure as defined in claim 2 wherein adjacent edges of theindividual walls extend from said spaced surfaces along convergingplanes.

4. A structure as defined in claim 2 further including a continuoussheet disposed substantially parallel to said surfaces and attached tothe free ends of said Walls.

5. A structure as defined in claim 1 wherein said walls are flexed to anangle approaching from the plane of said surfaces and are bonded theretoto provide openings of generally rectangular configuration.

6. A structure as defined in claim 1 in which the like spaced surfacesare of generally square configuration and are disposed in rows with thesurfaces of adjacent rows being in staggered relationship and whereinthe planar walls extend between the spaced surfaces in adjacent of suchrows and are connected thereto along planes which are coextensive withedges of such surfaces.

References Cited UNITED STATES PATENTS 3,642,566 2/1972 Figge 161-1273,214,319 10/1965 Graham 15662.2 3,666,607 5/1972 Weissman 161-4092,653,889 9/1953 Hager et a1. 161-417 3,668,052 6/1972 Pratt 16l117GEORGE F. LESMES, Primary Examiner J. J. BELL, Assistant Examiner US.Cl. X.R. 1611l7 UNITED STATES PATENT OFFICE CERTWECATE OF CORRECTIONPatent No 3 Dated SBP'tGmbQE' Ll Inventor(s) Theodore H. Fairbanks It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shownbelow:

Col. 1, line 66, "structure" should read structures Col. 2, line 51,"immaterail" should read immaterial Col. 3, line 19, pivotting" shouldread pivoting line 62, "terminalogy" should read terminology Col. 6,line 6, "designates" should read designate line 7, "iaining" should read0 maining Col.- 7, line 11, "wth" should read with Signed and sealedthis 18th da of December 1973.

(SEAL) Attest:

EDWARD M. FLETCHER, J'R. RENE D. IEGTMEYER Attesting Officer ActingCommissioner of Patents FORM FWD-1050 (10-69] USCOMNHDC aoanhpag v ".5.eovcqmqgm' uni'rms'orncz: was o-ass-sse

